Testing of recycled oil field wastewater used on about 45,000 acres of farmland in the Central Valley shows the water contains small amounts of potentially harmful chemicals, including oil, benzene and acetone.
Local water regulators in April ordered comprehensive testing of the irrigation water to check for the presence of chemicals used in oil production.
As California's drought continues, more companies and irrigation districts are seeking permits to sell and use treated oil field water. The heightened interest has raised concerns over the adequacy of current safety measures to prevent produce from being contaminated by oil production fluids.